


From Within the Core

by StripestheBoar



Category: Undertale (Video Game)
Genre: Flashbacks, Friendship, Gaster disappears, Grillster, M/M, Origin Story, Romance, before Gaster's fall, in the past, of course, pretty happy all around, so you know it might be a little sad
Language: English
Status: In-Progress
Published: 2017-11-24
Updated: 2017-12-10
Packaged: 2019-02-06 04:42:06
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 7,528
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12809856
Author URL: https://archiveofourown.org/users/StripestheBoar/pseuds/StripestheBoar
Summary: The story of Gaster and Grillby, and how they met and how they learned to get along and adapt, all before the infamous incident that changed everything.





	1. Prologue

**Author's Note:**

> *starts writing a Grillster oneshot* *ends up starting an entire Grillster chapter story* WHOOPS MY HAND SLIPPED HOW DID THAT HAPPEN?!
> 
> I really did intend for this to only be one chapter but… fuck.
> 
> Just so you know, this will be Grillster. All of it. Consider this the prologue.

Grillby didn’t speak often. Many monsters chalked this up to the fact he didn’t ever speak English, the language of most monsters that inhabited the Underground. He could understand it just fine, but with the way he crackled and hissed his speech, being able to comprehend it was almost impossible on the listener’s part. Listening was easy, but talking was the problem.

He knew someone like that once.

Sure, he had Zuzu, his translator, but even still, he didn’t speak all that much. The bartender was certainly a demure one, preferring to listen to the chatter at the tables and the enjoy camaraderie within his bar. It was quiet some days and rowdy during others, but he’d have it no other way. He enjoyed his life as it was now. He had a nice cozy home within Snowdin and a beautiful daughter he loved more than anything, even if she could be a bit of a brat at times. He counted himself as lucky for being in his position, doing something he loved with people he enjoyed being around. Patrons ranged from all shapes and sizes, each of them with their own stories to tell and friendly greetings to everyone.

Still, there was someone missing, and yet always there.

One of his favorite patrons was Sans, and though the smaller monster had enough debt to sink an entire economy, he was still a good friend nonetheless. Sans was always the one to do the talking, making jokes and occasionally buying a drink and playing a prank. His favorite one had to be where Grillby would be distracted with grabbing a glass. Sans would always be quick to grab his drink and take a swig, immediately spitting out a short stream and onto Grillby’s flame, causing it to flare up wildly. The bartender would then turn around just in time to see the skeleton falling out of his chair as he died from laughter. As insufferable as he was, Grillby would admit that it was rather amusing. It wouldn’t be long, though, before Papyrus would inevitably come in and make a fuss about Sans spending all his time there. The smaller one would make a joke and the larger would get peeved and stomp his foot before leaving with Sans tucked under his arm. The cook always wondered how the two even lived together when they seemed to far apart personality wise. One was messy and playful while the other was kind and serious about his work. Still, it seemed to fit together in a familiar way.

It was like someone he used to know.

But he just couldn’t remember who.

There was another reason why Grillby didn’t speak much; he didn’t have much to talk about. Whenever he thought back, he could only see a blur that used to be his past. He could remember where he came from and his home, but as the memories went further, they seemed to muddle together and blur like watercolor whenever he thought back to those days. It confused him to no end, but over time, he had learned to ignore it. Still, it didn’t help whenever the patrons got a bit chatty.

“So Grillby, what brought you to Snowdin of all places? Isn’t that, like, the opposite of where fire monsters are supposed to be?” a customer would ask.

“He says that Waterfall is probably the real opposite,” Zuzu would reply for him.

“Yo Grillby! Where’d you end up learning English so well, anyways?” another curious drinker would ask.

“He says from someone who knows English,” Zuzu would shrug.

“Hey Grillbz, is there anyone else who can understand that crackling thing you do?” Sans has asked. “I’m sure they don’t think you’re too  _hot_ to handle.”

“He said that’s like the sixth time you’ve made that joke, Sans,” Zuzu had replied. “If you say it again, he’ll kick you out.”

Grillby didn’t enjoy having to avoid all these questions, but he really didn’t know how else to answer them. He found it easier for it just to not be said.

Still, he couldn’t help but snag onto those fragments of memories.

He used to talk, and he used to talk freely and as much as he liked, that much he knew. He would crackle out his laughter and lay back as he listened and spoke, but with who, he just didn’t know. It wasn’t that he was constantly being reminded, but that something wouldn’t let him forget.

During silent nights at the bar, as he was closing up, he couldn’t help but shiver whenever he felt a chill. He would look up and towards the window, and if he was fast enough, he could catch a glimpse of gray, maybe even a bit of black. He would move towards the window and look out, expecting to see a monster or two walking about, but it would stay silent and still. And so he would go back to setting up the bar silently, perhaps hum a tune to himself over the crackling of his own fire until he would eventually go home.

Sometimes he felt as though something was always waiting for him to come back. It was a silly thought, he knew, and so he preferred to keep it to himself.

That’s why Grillby didn’t speak much.


	2. Something in the Pipes

**Summary for the Chapter:**

> We turn back time to see Gaster looking over his creation, though it might have a few kinks in the system.

Gaster leaned over the edge of the railings,  a cigarette to his teeth that filled his ribcage with smoke. Wisps of the gray vapor leaked from the openings of his white turtleneck, only to be lost in the air wavered by the Core’s heat. He let a sigh, thr grin on his skull stretching more as his frame relaxed in the heat.

 The day had been relatively sluggish for Gaster. With the Core long since completed, he found himself at ease for the past few month, years of overworking himself having taken its toll on his soul. As dull as they could be at times, he still enjoyed the slow days, his only real responsibilities being checking up on his assistants and the maintenance of his pride and joy. Despite his protest, Asgore had strictly ordered him to take it easy for now, wanting him to recover from almost killing himself from exhaustion. So, as of now, Gaster executed his responsibilities and made sure everything was in order. That was what he was doing this day, and he expected it to be just the same as any other day.

“It looks great, Doc,” his assistant commented, approaching his superior with a small smile on his face. A smaller rabbit monster from Snowdin, Cot was a cheerful and eager young mind, if not just a bit on the dull side when it came to large projects such as this. “Not a single pipe burst in nearly a month.” Gaster couldn’t help but grin to himself, leaning further onto the railing overlooking the magma pit that the entire structure was perched over. The hot material could be heard moving sluggishly through the pipes, being used to power the entire Underground. A feeling of pride welled up inside of him as he looked upon the well-running machines of Hotland, the fruits of his hard labor. “Everything is running smoothly,” he hummed, his magic spelling the symbols directly above him for the other to read. Everyone who knew the monster would have to be able to decipher these symbols if they truly wanted to communicate with him, as his natural dialect was almost indecipherable. 

“Go home,” he told his assistant. “You’ve earned it for today. I’ll wrap up with few more status checks of each focal point. Should only take a good fifteen minutes.” His assistant nodded dutifully before wishing him well and leaving for the day. Gaster watched him leave, finishing up his cigarette and crushing it between his phalanges. The heat didn’t bother him; it didn’t bother any skeleton, really, as their bones were rather tough and resistant to extreme temperatures. With a flick of his wrist, he tossed the crumpled up filter into the heat below, soon to burn and be forgotten. He watched the scorching magma bubble and churn, finding a soothing comfort in it. It calmed him in a way.

As he had said he would, he made his rounds through the Core, making sure everything was in a perfect state before he could leave for the day and go home for a well deserved nap. However, just as he was about to hand up his lab coat and head for the door, he suddenly heard a loud thump in one of the pipes. Gaster jumped slightly and furrowed his brow ridge, looking over at the array of metal tubes that were used to transport the magma around the Core. His eyelights quickly inspected them for any trace of a collapse or dent in the sturdy metal, but it all looked clear. It must have just been a rock that had gotten caught in the flow of the lava, not yet molten by the heat. Perhaps it had fallen from the roof of the cavern, quickly sucked up by the pipes underneath the Core.

He let out a sigh and turned back around to grab his work satchel, when he heard it again. It was a loud thud, like something heavy had crashed into the inside of one of the large pipes, this time further down the system than before. It was as if the sound had moved with the flow of lava. However, when he checked again, there was no damage to the pipes, which is something a large rock would have cause should it have hit the metal with such force. Despite the lack of damage, his curiosity and worry grew and he decided to follow the pipes back to the center to see what exactly was causing the noise. His main guess as of now was that somehow a large rock had been sucked into the pipes and needed to be removed. It wouldn’t be the first time, but damn was it a pain.

As it turns out, he got his answer sooner than he had expected.

He followed the metal pipes at the same pace as the noises, the thumping slowly growing louder and louder with Gaster’s worry directly increasing as they went on. He prepared a few bones and magic hands in case something gave way. Pipe bursts were unexpected and needed to be fixed immediately lest they risk the Core becoming unstable, which would lead to power outages and just a general mess of a problem all around. Luckily, there were emergency cooling systems and tools all around. 

Funnily enough, everything seemed just fine, despite the banging.

Then, without warning, one of the pipes suddenly burst open, spewing out a torrent of magma. “WHAT IN GOD’S NAME-?!” In his surprise, Gaster was quick to block off the pipes using his magic, hand apparitions quickly grabbing tools and bolting the metal back into place as the emergency cooling systems were activated. Steams of water were sprayed down onto the pipe to cool the searing lava. Attempting to avoid the molting hot liquid, he stepped back, only to be surprised to see something moving about in the rapidly cooling magma and away from the water.

At first, Gaster thought something had caught on fire, until he saw the way it moved so rapidly, almost like an animal in panic. It glowed brightly with the rest of the liquid rock, and crashed into walls and pipes wildly before collapsing onto the floor, where Gaster could clearly get a good look at it. 

On the floor, clearly in a more humanoid shape, was a being made of bright orange and yellow fire, with its flame-shaped head flaring and flickering wildly. It had perfectly shaped limbs, and from the way it used them to cower and back away, Gaster could tell it was afraid. The scientist made quick work of the mess that was caused, before hurrying over to fire monster. 

The flame that was the monster’s head seemed to turn up to look at him, and in an instant it tried to scurry away. “Wait!” Gaster called out to him, despite his speech being incomprehensible. As expected, the fire monster didn’t even pause, scampering to get away as quickly as possible. It leapt up to its feet, stumbling a little, before dashing down the corridor in a flash of light. As soon as it passed a small plank of wood from earlier construction, the piece immediately caught fire, blazing brightly like it had been doused in gasoline. “Oh dear,” Gaster muttered to himself, quickly bolting after the other with lightning speed. What came next was a wild chase through the Core, everything the fire monster passed bursting into a roar of flames. The flaming spirit kept crashing into walls and pipes on accident in its endeavor to escape, lighting up the halls like a walking furnace. It wasn’t until he came to a dead end at the balcony was he forced to a stop, almost hurling himself over the railing in his haste to get away. Gaster stumbled onto the balcony that overlooked Hotland, his bones aching and his magic near depleted in his effort to put out each fire he had come across. The fire monster backed up against the railing, looking down at the drop as if to weigh its options. Gaster stopped in his tracks, afraid that any slight movement would provoke the flame to leap into the vast magma pit and never return. The fire crackled like a burning log, the flame of its head swinging wildly as it seemed to look around for another escape route. Gaster knew at this point that he needed to be cautious with his actions, as any sudden moves would provoke the fire to leap over the edge.

“Hello,” he said softly, catching the other’s attention. Although his speech was near indecipherable, he hoped the gentle tone of his voice would be able to calm to scared creature. “I’m not here to hurt you.”  

Crackles and hisses of the fire were more than audible as the skeleton observed the strange monster, a clear warning telling him to back away. Despite deciding to go through with approaching the fire monster, Gaster remained cautious slowly stepping forward as he continued to speak softly. “Do not fret. I’m of no danger to you.”

The monster stilled, presumably staring at him intently for anymore movement. Gaster did the same, making sure he didn’t want to rush it. “I know you’re afraid, but I don’t want to hurt you.” After a few moments, he stepped forward again. The monster’s reaction was violent, quickly raising a limb threateningly towards the scientist. Before Gaster could react, he was quickly hit by a ball of fire, causing him to stumble back in surprise as his coat and sweater burned. He was quick to put it out before the fire took any more of his HP. He looked up at the fire monster to see it preparing another attack, watching him carefully and waiting for him to take another step forward. Gaster held his breath, checking his stats to see where his HP was at. Surprisingly, the ball of fire only knocked off a single point, hardly doing any damage to him at all. A crackling hiss came from the fire, another warning for him to stay back.

Against his better judgement, Gaster only ignored  the message, stepping forward and raising his hands to try and reason with the other. Within an instant, another ball of fire was hurled towards him, but the scientist was quick to avoid it. This only caused the fire monster to panic, quickly shooting more bolts of flames at the skeleton in an attempt to get him to flee. This was to no avail however, for as even though Gaster wasn’t able to avoid all of it, he still continued to approach, and within seconds, he was mere feet away from him.

The monster hissed and crackled, preparing another attack, only to be stopped when Gaster quickly grabbed onto its forearms. The flames licked at his bones, already threatening to char them. He could feel his HP depleting ever so slowly just by grabbing onto it. The monster’s reaction was less than calm, trying with all its might to pull away with no results. So instead it shielded the flame of its head, almost like a child attempting to hide away by raising their arms above their head. Gaster could feel his soul soften at the motion, and with that his grip lessened. The flame was quickly to tug its arms away, cowering before the other. The skeleton frowned, placing a gentle hand on the other’s back in an attempt to calm him, and to his surprise, it seemed to be working. The monster seemingly looked up, though without clear indicators of features it was near impossible to tell. He decided to take this opportunity to try again once more.

“See?” he whispered softly. “I won’t hurt you.” He cautiously raised a hand to take the flame’s hand into his, grabbing it softly. He finally noticed that fingers were fully formed, the monster being a perfect model of a human made of fire. The flame was quick to tug its hand away, but on a second try, he wasn’t so reluctant. It even gripped Gaster’s hand back, no longer scorching the skeleton or lowering his HP. He exhaled in relief, glad he was able to calm the monster down. However, there were still more questions to be had.

“Now to find out what you are,” he sighed. “I’ve never seen anything like you before.”

The fire monster merely tilted its flaming head, still very afraid, but now more confused than anything. 


	3. The Lab

**Summary for the Chapter:**

> Gaster struugles to welcome his new guest into his lab.

Getting the monster to follow Gaster back to his lab was a fairly difficult endeavor, to say the least. It was certainly a test of patience, as anything that even moved made the flame immediately anxious and stop in its tracks. He had thought about using his gravity magic to help move the flame along, but he knew it would only end up badly. Though there was little damage done to his HP, Gaster had enough burn marks on his clothes as it were, and he didn’t want to lose the already thin bit of trust he had gained so far. And so it was at a snail's pace they moved, slowly inching along further and further while several Hotland monsters watched from afar. Some even tried to approach him, curious of the new monster. but Gaster warned them away; the monster would possibly have a soul attack if a stranger attempted to interact with it. Well,  _if_  it even had a soul in the first place, that is. He was sure it did, as almost every creature had a soul of its own, save for plant life or microorganisms. It was unheard of for any sentient creature to not have a soul of its own. If it didn’t, though, it would make things a tad more complicated in the lab. More complications were just what he needed at a time like this. 

Once they were in the lab, Gaster was quick to shut and lock both exits just in case the monster got too panicky. He slowly let go of the flame go, motioning for it to stay right there, before going to check if there was anyone in the main lab, which there was none after a small scan. That was to be expected, as he was the only one with authorized access. The only ones really there were the subjects.  

When he returned to retrieve his discovery, he was surprised to find it gone. In a panic, he hastily began checking upstairs to find it before it got into any unwanted trouble, only to come across the monster looking curiously over his workshop table. He gave a small sigh of relief, glad nothing had happened while he was away. That’s when the table suddenly caught fire. 

Gaster nearly lost his cool attempting to grab the fire blanket, tripping over his own feet in his haste to put out the fire. Once the burning desk was smothered, he checked to see if anything was damaged beyond repair. Luckily, he had stopped it just in time. “You really have to be more careful,” he huffed, looking over at the fire monster. The flame in question had moved onto the shelves, lined with over a hundred books. It slowly reached out to touch one of the leather-bound works, seemingly curious about these, too. Gaster strode over just in time to see one of the books catch fire, the heat beginning to spread onto the other works of literature. “Oh dear,” he whispered to himself, grabbing the blanket and using it to quickly smother that fire as well. He could now see where this was going. He quickly turned his skull, noticing the fire spirit was watching him for a few moments, before deciding to carefully walk over to his desk, where many research paper were stored. At that moment, he was more than tempted to throw the blanket onto the fire monster itself. 

“Whoa whoa!” Gaster called out to him, dashing over and scaring the monster. He firmly, but not too forcefully grabbed it by the arm, gently trying to lead it away from the indubitably important work he had gathered over the past few months. “Okay, listen,” he sighed, catching the monster’s attention. “It’s essential that you stop setting every damn thing you see on fire. Some of these objects may be foreign to you, but they are more than important to me and the kingdom of monsters. So please. Stop. Burning. Things.” 

The monster’s flame crackled and hissed as expected and he sighed. “You didn’t understand a word of what I said, did you?” More crackling and hissing. “Fine. I suppose a demonstration is in order.” He went over to his tool box and grabbed a torch and a small rag. He turned to the monster, whose attention was focused on him. He lit the rag on fire, shook his head, and put the fire out. The flame continued to stare, making it unclear if he even understood the visual demonstration. He couldn’t blame it; the spirit came from within the Core, which were filled with pipes of liquid fire. Speaking of which, he needed to get someone down to properly fix the pipes. If the Core was able to suck up a fire monster, it could easily happen again, and another confused and scared monster was not what he needed right now. The main question now, though, was what to do with the monster. It obviously already had a home and was understandably rather scared, but he couldn’t help but think of the value of the research. He had never seen a monster made completely of fire; it was unheard of, and he had never heard of any being on the surface beforehand. However, there was also the setbacks; he didn’t know the monster’s age, name, or even gender, and god knows if it was even able to speak. It obviously had no concept of the things around it, and he greatly doubted it had a form of writing he could decipher. There was also the fact that Gaster himself spoke in a dialect almost unknown to everyone, forcing him to use symbols to explain himself.  

He sighed and glanced over at the monster, who seemed too afraid to tough anything. It also didn’t wear clothes. That would be a bit of a problem now, wouldn’t it? He didn’t think a monster made of fire would be too happy about being forced to wear clothing.  

Perhaps Asgore would know. The king of the Underground had more than a century and a half under his belt; surely he would know what this spirit was and just what to do with it. Though it would be more than likely that he would force Gaster to let the flame go back to his natural habitat, he did suppose he would have a day or two to study the monster before letting it go. 

Gaster looked at the time. It was getting rather late and he needed to get home. However, he couldn’t just leave a fire monster here, lest he come back to see the lab in ruins. He thought about bringing he flame home himself, but realized that he would have to pass though Waterfall no matter which way he chose. A monster made of fire and Waterfall would not mix well. 

After a few minutes of thinking on the subject, he made the decision to stay here for the night. The lab was equipped with a bed should a situation such as this arise and he was left without the ability to get back home. Now he just needed to figure out how to get the flame monster to sleep, if it even could sleep in the first place. 

‘Flame monster’, he thought to himself. A bit of an odd name, but the only name he had for it. He attempted to think of something else he could call the fire spirit. Names such as “Sparky” or “Smoky” came to mind, but they were quickly disregarded; he was in possession of a fire monster, not a dog. It seemed finding something to call it would have to be postponed. 

“I suppose you’ll have to go nameless for now,” he sighed to the flame monster. “I’d rather not always refer to you as ‘fire monster’, but seeing as I don’t even know your gender, I suppose I have no other choice.” 

The monster gave its usual crackles and hisses in response, the sounds typically made by burning logs. The noises were loud, but would die away every now and again. “I don’t even know why I’m explaining all this to you,” he muttered, before leading him down the stairs. “It’s not like you’re able to understand me.” The crackling grew louder again and died away. He stepped over to his cabinet full of supplies, wondering what a flame monster would sleep on.  

“Anyways, I suppose I should find a suitable way for you to sleep before I go to bed as well. Though, I’m not sure if your kind can even sleep.” The cracklings and hisses grew and fell. A bit of a coincidence they seemed to fluctuate in volume as he talked. It was almost like it was responding to his voice, but that in itself was rather absurd, seeing as it couldn’t even speak. 

Wait. 

Gaster paused, slowly turning around to look at the monster, who stared back with unreadable emotions. The noises rose and fell once again, changing in pitch every now and then before it was gone. However, the sounds were strangely organized, now that he thought about it, and lord knows he didn’t believe in any type of coincidences. 

“Are you… speaking?” he murmured softly. The flame did not react, but the noises fluctuated once again. Those were definitely in a type of pattern. “You are. You’re attempting to speak,” he realized, his voice matching his astonishment. “Can… you understand me?” The fire did not make a sound. He would take that as a negative, but that didn’t matter right now. He was now almost absolutely certain that the monster before him had an actual language he was able to speak. This was, to say the least, exciting, meaning that communication was indeed possible, though very difficult. 

Filled with a newfound ambition, Gaster went into the supply closet and pulled out an old mattress of his with a bit of difficulty. He dragged it to the middle of the room, the fire monster watching him as he did so. He laid the mattress down and pointed to it. “Hopefully this will suffice. I don’t mind if it ends up on fire; the floor is made of metal, anyways.” The fire monster stared blankly, unresponsive. “Fine. I suppose another live demonstration is in order,” Gaster muttered, removing his lab coat and lying down on the mattress. “Like this, see? You can sleep, can’t you?” He pat he exterior of the cushion below him, and it had an immediate response. The flame approached and crawled onto the mattress beside him. At first, it looked surprised by its soft texture. It paused for only a moment before bouncing its frame on the cushion as a sort of test. Within a few seconds, it was rolling around on the softness of the mattress, its crackles and hisses becoming louder as it seemed to speak to itself. Gaster sat up with a nod. “I can see you’re enjoying your bed,” he told the monster, getting up and coming to a stand. “Hopefully nothing bad will happen overnight.” To his surprise, though, the flame got up as well, coming to a stand. He furrowed his brow bone, pointing to the bed once again. “Don’t you like it?” he asked. “You seemed to adore it a few seconds ago.” The fire monster tilted its flame, not understanding. He grumbled and laid back down again. As expected, the fire followed suit, but once he tried standing up again, the other did the same. 

“Oh no…” Gaster murmured to himself. “Please don’t make me...” The fire monster stared blankly, being unable to respond. “Fine. I suppose I have to do what I have to do. For science,” he huffed, lying back down again. The spirit was hesitant to do the same. “But this is for science and science only!” Crackles and hisses were the only response. Gaster sighed and stared up at the ceiling, wondering where this little accident was going at this point. The monster seemed contented enough, though. He turned over on the mattress in an attempt to sleep, hoping he wouldn’t wake up on fire. 


	4. What is it?

**Summary for the Chapter:**

> Gaster takes the fire monster to Asgore to find out more about it.

Upon his awakening, Gaster awoke to find that he was still alive and not, in fact, a charred pile of dust. He sat up slowly, confusion expressed over his skull as he recalled the events of the night before. He hadn’t even realized he had fallen asleep, too lost in his own thoughts to realize he had been drifting off. Fortunately, though, the monster beside him did appear to be asleep. Its flames had lowered a substantial degree, the color now a soft red, the coolest part of the fire in terms of color. Gaster found himself watching the flame quietly, observing the way the small wisps of fire danced and slid in the air. He was glad that he now knew the monster could sleep, but it also meant that it probably had other vital issues similar to most monsters. The hardest part would be finding out what it ate. He didn’t suppose it could survive long without food, but the type sustenance was the question. Anything liquidated would probably be a disaster, and he felt as though it wouldn’t work out too well if he gave the monster a log or threw sticks at it. Hopefully the king would be able to answer these questions. For now, however, he would let the fire burn low, reminding him of simmering water. It wasn’t too hot, but you could definitely see the beginnings of what could be. 

Gaster pulled away, deciding to go down to the main lab and take a look to see how the subjects were doing. It would only take a good ten minutes, as they didn’t need that much attention. After that, he made sure to message his assistant, Cot, to check on the core and make the proper fixes. Once the structure was secure, the rabbit monster would be able to take the day off. 

‘I’m entrusting you with this only because I have my hands full at the moment,’ he texted the less experienced scientist, his words coming up as the familiar symbols associated with his speech. ‘Remember to check the vitals twice before leaving for the day. The core is in a very fragile state.’  

The reply was rather quick. ‘No problem, Doc. I’ll be thorough. I’ll get a group to work on it.’ 

That left the skeleton satisfied, if not a bit iffy. Cot was a brilliant young man, though a bit of a slacker and a procrastinator, with a track record of clumsiness to top it all off. Still, should there be any dire emergencies, Gaster would be notified through his phone. The best-case scenario would be a power outage. The worst case would be the blasted thing blowing up, though that was on the more unlikely side.  

Tucking his phone back into his pocket, Gaster rode the elevator back up to the surface lab, where the fire monster was there, awake and looking around. Thankfully, the only thing on fire was the mattress. It wasn’t anything important like his work, reducing some of the stress that was already mounted on his back. He quickly put it out with a fire extinguisher, since the fire blanket was already a mangled mess. The flame looked over at him, his fire once again a soft orange, with a flickering core of yellow just barely noticeable. 

Beckoning him over, Gaster grabbed his lab coat, almost about to pull it on when he noticed that a large portion of his turtleneck was still burned away. While his burns had healed overnight, clothes didn’t regenerate as easily. Or at all, really. It wasn’t like he had other shirts here. A bit embarrassed, he pulled on his coat and made sure to close it and button it up, covering most of the mangles sweater and only exposing its singes neck-cover. 

“Come along,” he ordered the monster, gesturing to the door. “We have a meeting with the king to attend to.” Gently grabbing it by the arm, he led it outside, making his way to the Core to pass through it and up to the castle. 

* * *

 “Sire…” 

The king paused for a moment, looking back curiously as he lifted the watering can he was using to care for his garden of buttercups. He recognized that distorted voice from anywhere in the Underground. “Gaster! Ah, come in come in,” Asgore greeted, his mood instantly shifting to a more jovial tone. Still, the skeleton hesitated, looking over behind the doorway at something the good king could not see. “How many times do I have to tell you to just call me ‘Asgore’? Anyways, I was just finishing up with my flowers. Would you like a cup of tea?” He tilted his head. “Seems a little early for you to be handing in your report. A whole three days early at that.” 

“I have a bit of a problem, your highness,” Gaster confessed, his words taking form of symbols that appeared above his head for him to read. Asgore frowned, noticing he had yet to step onto the grass. “A problem? Well, whatever it is, I’m sure to help in any way I can,” he rumbled. “Whatever could it be?” 

Gaster seemed reluctant, but gave a nod and turned to whatever was behind the doorway, seemingly beckoning it over. Within a moment, a fire monster was brought in, being forced to stop just short of the grass by the skeleton. This understandably filled the boss monster with surprise. The flame in question seemed to be just as surprised, already trying to pull away and cower. However, it was kept in place by the monster who brought it here. Asgore fell silent, his brow furrowed as he looked to Gaster for an explanation. 

“I, er, came upon it in the Core,” he explained. “It seems as though he was sucked up by one of the pipes and happened to break its way out.” He glanced over at the fire, making sure his grip was tight. “I was hoping you might have some insight, seeing as you’re the oldest living monster.” 

Asgore gave a faint nod, stepping out into the corridor. As he came closer, the flame became more frantic to pull away. “Now now, there’s no reason to be alarmed- for the love of god, stop moving!” Gaster grunted, wrapping both arms around it to keep it from escaping. The fire of the monster’s body only rose as his distress mounted, catching the doctor’s coat on fire in an instant. “Gaster, that’s no way to treat him. Look, you’re only scaring him more.” 

“Well,  _your highness_ , he’s trying to get away! He is highly flammable and will set anything on fire if he gets loose and- wait.  _He_?” Gaster paused in his rant to look up at his king with a confused expression. “Yes, it is a he,” Asgore rumbled, dropping down to a knee to get closer to their level. “Now, let go of him.” 

“But Asgore, I-“ 

“That’s an order, young man.” 

Gaster let out a frustrated huff and reluctantly complied, letting the flame go, taking a moment to tear off his flaming coat and throwing it on the ground and stopping on it so it wouldn’t be completely incinerated. As expected, the monster leaped back a few paced, stopping after a fair distance to stare back at them. The two were silent, staring back as the flame watched them cautiously. Asgore smiled warmly at the fire, offering a hand to him. “It’s alright. You’re safe here,” he assured him softly, gesturing for him to come back over. The monster was obviously hesitant, but slowly made his way back over, seemingly constantly glancing at Gaster. Picking up the hint, the skeleton steadily approached and helped guide him over, also giving soft words of reassurance. The fire looked down at the offered hand hesitantly, before gently taking it. Immediately Asgore felt a burning sensation, the fur on his hand beginning to singe and burn. Still, he clenched his teeth and stuck through it, gently gripping the other’s hand; he’s been through worse than just grabbing literal fire. Was it painful? Yes. But was it also necessary? Very. 

The monster’s flames gradually lowered, showing a steady calm take over him as the burning lessened. “There. Better?” Asgore hummed, pulling his hand away. “Excuse my language, sire, but what in the name of the Underground was that about?” Gaster blurted out, looking puzzled. “What exactly is he? I can assume you’ve seen one before?” 

Asgore gave an amused smile, getting up to his full hight and gesturing for them to follow him back to home. “Several times, actually. He’s a fire monster,” he explained, “though I’m sure you could have figured that out without me ever telling you.” Gaster followed, matching his pace right beside him. The flame trailed behind, looking around as they walked. “So where do they come from? Why haven’t we seen one until now?” the scientist asked, pulling out a small notepad and pen to jot things down. 

“To be honest? I’m not sure why we haven’t seen one,” he told him. “Though, I suppose they all just moved out once we moved in. They lived underground far longer than we ever had. The only time we’d ever really get to see one was after volcano eruptions, where a few would be forced to the surface. Unlike most fire-based monsters, however, your little friend here has a particularly fragile race; any contact with water is the fire equivalent to dipping your hand into acid.” 

They entered Asgore’s home, where he took them to the kitchen. “Unfortunately,” he continued, frowning at a particularly harsh memory, “they couldn’t stay long. Eventually it would rain, or maybe it would flood. Either way, they would die as soon as they were caught in the water. This is very unlike monsters such as Vulkins and Pyropes. While their fire can go out or their lava can harden, it can all regenerate and they’d only feel slightly sick. Fire monsters are completely made of flames, and will die if exposed to too much water. Sure, some would herd up inside homes, but they couldn’t comfortably stay on the surface and would eventually have to return to their original homes. They mostly live in lava-based areas, from what I’ve learned.” He brought them to the kitchen, where he dug through the pantry for something in the back. “They’re rather fascinating. They have their own language, culture, history, and even practices and rituals, like you saw.” He turned back for a moment to show his singed up hand. “Fire monsters enjoy burning things, understandably. To them, letting one burn you is polite and means that you mean them no harm, but pulling away has them make you out to be unfriendly or hostile even.” He turned back to the pantry to try to find what he was looking for. 

Gaster looked back at the monster, watching him curiously look around the kitchen and open cabinets. He seemed surprised when he found out that the cabinet was actually a giant hole for putting things in instead of being solid wood. “So how did you know it’s gender?” he asked, turning back to his king. “Ah, here it is,” Asgore smiled, pulling out a small bag of charcoal and a bottle of lighter fluid. He used to use these for barbecuing way back when. “Color,” he answered. “Males are usually warmer colors, like red or orange, while females take cooler colors, such as blue or green. They can change tones depending on intense emotion, though, and when they sleep.”  

He picked out a rough looking piece of charcoal from the back, offering it to the monster. The flame immediately took interest from looking at the toaster to walk over and take it into his hand. In a second, the flame that was his face split open on the front and he immediately popped it into the gaping cavity, snapping it shut and letting out a pleased crackle. Asgore chuckled and handed him the bottle of lighter fluid, giving it a light squeeze so some could spray on the monster himself, causing its flame to flare up wildly. It quickly took up the bottle, squeezing a large dose of the liquid into its mouth with a happy coo. Gaster took a moment to pick his jaw up off the floor, just watching the monster. “Asgore… what do I do with him?” he asked slowly, still processing it all. 

Asgore smiled, handing the flame another piece of charcoal. “Return him,” he said simply. “Teach him some about our world, and then bring him back to his own world. I’m sure he misses it dearly, but if you teach him well enough and bond with him, he may just want to come back.” He smiled warmly, watching the fire monster eat happily. 

Gaster nodded slowly, now feeling a mew weight on his shoulders. “But… what should I name him?” He asked. “What should I refer to him as?” 

“Hm… I suggest you call him Flame!” Asgore suggested. 

“Er, on second thought, I’ll come up with the name,” he replied politely, letting out a soft chuckle. “So… you mentioned tea?” 

* * *

“Vitals seems fine,” Cot muttered to himself, overlooking the stats of the Core. “Looks like the Doc did a pretty good job after all.” He looked over at the pipes, grimacing at the shoddy look of the temporary fix. “A pipe burst, huh? Wonder what happened. Looked like it was going fine before I left.” He shrugged, going over to the Core’s edge to take a look at the state of the pipes on that side as well, not wanting there to be any discrepancies. As he got closer to the edge, though, he felt himself grow rather nervous. Some of the Core’s outer platforms had yet to be given a railing, and while it made him a bit uncomfortable, he knew he had nothing to worry about. 

“Pipes look good over here, too,” he muttered, jotting down the vitals. With how easy the task was, he might as well call his mom now to tell her he’d be home in an hour or so. It depended on how long the river person liked to ramble. 

All of the sudden, without warning, a burst of steam suddenly traveled from one of the steam valves, surprising Cot near half to death. He leaped back in surprise, letting out a yelp when he took another step back and lost his balance, nearly slipped off the edge of the Core. He gasped in surprise, swinging his arms wildly and dropping the clipboard on the ground in an attempt to regain balance. He did so successfully, quickly backing away from the edge like it held a deadly disease. His soul beating with an intense fear, he tried to dissipate his terrified feeling over his near fall into the very hot lava with a nervous laugh. “F-fuck!” he swore, chuckling to himself fearfully. “Ha, I better get to calling about those railings. Who knows what would have happened if I fell in?”  

He gulped, going over to retrieve his clipboard, taking a quick glance down at the churning magma below before hurrying out of the Core. 


End file.
